House Republican insiders acknowledge a shutdown is increasingly likely, due to House conservatives’ aversion to passing a “clean” continuing resolution that simply funds the government. But the leadership isn’t ready to concede defeat. Behind the scenes, Speaker John Boehner and his allies are finalizing their strategy for the eleventh hour: a last-minute CR play.

Here’s how it could unfold, according to sources familiar with the leadership’s closed-door deliberations.

First, the House passes a CR today that delays Obamacare’s implementation for one year and repeals the medical-device tax. This legislation will almost certainly die a quick death in the Senate.

Should that happen, the House will send another bill back. The leadership is mulling several options. At the top of the list is a revised CR that includes the Vitter amendment, authored by Senator David Vitter (R., La.), which would eliminate Obamacare subsidies for congressional staffers and members.

The leadership thinks that a final CR with Vitter’s language would put them on solid political ground, even if Senate Democrats resist. In that scenario, and the government shut down, Republicans would argue that Democrats shut down the government to protect their perks.

The leadership also believes Senate Majority Leader Harry Reid would feel pressure to take up such legislation, especially from red-state Democrats who are up for reelection next year.

But that’s just one of the options being bandied about at the Capitol. For the moment, House leadership is more focused on keeping Republicans united, should things get wild in the coming days. The conference’s unity is fragile, and any new plan will need to be unveiled carefully.